[PATCH v7 00/20] CoreSight: Refactor power management for CoreSight path

[Leo Yan]

This series focuses on CoreSight path power management.  The changes can
be divided into four parts for review:

  Patches 01~07: Refactor the CPU idle flow with moving common code into
                 the CoreSight core layer.
  Patches 08~15: Refactor path enabling and disabling with range, add
                 path control during CPU idle.
  Patches 16~17: Support the sink (TRBE) control during CPU idle.
  Patches 18~20: Move the CPU hotplug flow into the coresight core layer
                 and simplify the code.

This series is rebased on the coresight-next branch and has been verified
on Juno-r2 (ETM + ETR) and FVP RevC (ETE + TRBE).

---
Changes in v7:
- Added a flag in coresight_desc to indicate CPU bound device (Suzuki).
- Used coresight_mutex to protect per-CPU source pointer (Suzuki).
- Added a spinlock for exclusive access per-CPU source pointer (Suzuki).
- Dropped .pm_is_needed() callback (Suzuki).
- Supported range in path enabling / disabling (Suzuki).
- Gathered test and review tags (Levi / James).
- Link to v6: https://lore.kernel.org/r/20260305-arm_coresight_path_power_management_improvement-v6-0-eff765d211a9@arm.com

Changes in v6:
- Rebase on the latest coresight-next branch.
- Always save and restore TRBE context during idle (Will).
- Use get_cpu() / put_cpu() when set the per CPU source pointer.
- Link to v5: https://lore.kernel.org/r/20251119-arm_coresight_path_power_management_improvement-v5-0-f615a301ad0b@arm.com

Changes in v5:
- Set the per-CPU source pointer on target CPU (Suzuki).
- Reused existed enable/disable buffer functions in TRBE callbacks
  (James).
- Refactored refcount for source devices in SysFS mode.
- Released path in cpu-hotplug off flow to avoid memory leak.
- Updated ETMv3 driver when move common code into core layer.
- Rebased on the latest coresight-next branch.
- Link to v4: https://lore.kernel.org/r/20251104-arm_coresight_path_power_management_improvement-v4-0-3d4bba674709@arm.com

Signed-off-by: Leo Yan <leo.yan at arm.com>

---
Leo Yan (19):
      coresight: Populate CPU ID into coresight_device
      coresight: Remove .cpu_id() callback from source ops
      coresight: sysfs: Validate CPU online status for per-CPU sources
      coresight: Move per-CPU source pointer to core layer
      coresight: Register CPU PM notifier in core layer
      coresight: etm4x: Hook CPU PM callbacks
      coresight: etm4x: Remove redundant condition checks in save and restore
      coresight: syscfg: Use spinlock to protect active variables
      coresight: Introduce coresight_enable_source() helper
      coresight: Save active path for system tracers
      coresight: etm4x: Set active path on target CPU
      coresight: etm3x: Set active path on target CPU
      coresight: sysfs: Use source's path pointer for path control
      coresight: Control path with range
      coresight: Control path during CPU idle
      coresight: Add PM callbacks for sink device
      coresight: sysfs: Increment refcount only for system tracers
      coresight: Take hotplug lock in enable_source_store() for Sysfs mode
      coresight: Move CPU hotplug callbacks to core layer

Yabin Cui (1):
      coresight: trbe: Save and restore state across CPU low power state

 drivers/hwtracing/coresight/coresight-catu.c       |   2 +-
 drivers/hwtracing/coresight/coresight-core.c       | 377 +++++++++++++++++++--
 drivers/hwtracing/coresight/coresight-cti-core.c   |   9 +-
 drivers/hwtracing/coresight/coresight-etm-perf.c   |  25 +-
 drivers/hwtracing/coresight/coresight-etm3x-core.c |  73 +---
 drivers/hwtracing/coresight/coresight-etm4x-core.c | 154 ++-------
 drivers/hwtracing/coresight/coresight-priv.h       |   4 +
 drivers/hwtracing/coresight/coresight-syscfg.c     |  21 +-
 drivers/hwtracing/coresight/coresight-syscfg.h     |   2 +
 drivers/hwtracing/coresight/coresight-sysfs.c      | 126 +++----
 drivers/hwtracing/coresight/coresight-trbe.c       |  61 +++-
 include/linux/coresight.h                          |  15 +-
 12 files changed, 546 insertions(+), 323 deletions(-)
---
base-commit: a90863095f84f6d17c49716e4e2212d28a6b25b5
change-id: 20251104-arm_coresight_path_power_management_improvement-dab4966f8280

Best regards,
-- 
Leo Yan <leo.yan at arm.com>